82 lines
1.9 KiB
Go
82 lines
1.9 KiB
Go
package uuid
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/****************
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* Date: 14/02/14
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* Time: 7:46 PM
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***************/
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import (
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"time"
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)
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const (
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// A tick is 100 ns
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ticksPerSecond = 10000000
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// Difference between
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gregorianToUNIXOffset uint64 = 0x01B21DD213814000
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// set the following to the number of 100ns ticks of the actual
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// resolution of your system's clock
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idsPerTimestamp = 1024
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)
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var (
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lastTimestamp Timestamp
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idsThisTimestamp = idsPerTimestamp
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)
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// ********************************************** Timestamp
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type Timestamp uint64
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// TODO Create c version same as package runtime and time
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func Now() (sec int64, nsec int32) {
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t := time.Now()
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sec = t.Unix()
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nsec = int32(t.Nanosecond())
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return
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}
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// Converts Unix formatted time to RFC4122 UUID formatted times
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// UUID UTC base time is October 15, 1582.
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// Unix base time is January 1, 1970.
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// Converts time to 100 nanosecond ticks since epoch
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// There are 1000000000 nanoseconds in a second,
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// 1000000000 / 100 = 10000000 tiks per second
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func timestamp() Timestamp {
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sec, nsec := Now()
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return Timestamp(uint64(sec)*ticksPerSecond +
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uint64(nsec)/100 + gregorianToUNIXOffset)
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}
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func (o Timestamp) Unix() time.Time {
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t := uint64(o) - gregorianToUNIXOffset
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return time.Unix(0, int64(t*100))
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}
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// Get time as 60-bit 100ns ticks since UUID epoch.
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// Compensate for the fact that real clock resolution is
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// less than 100ns.
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func currentUUIDTimestamp() Timestamp {
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var timeNow Timestamp
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for {
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timeNow = timestamp()
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// if clock reading changed since last UUID generated
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if lastTimestamp != timeNow {
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// reset count of UUIDs with this timestamp
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idsThisTimestamp = 0
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lastTimestamp = timeNow
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break
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}
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if idsThisTimestamp < idsPerTimestamp {
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idsThisTimestamp++
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break
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}
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// going too fast for the clock; spin
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}
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// add the count of UUIDs to low order bits of the clock reading
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return timeNow + Timestamp(idsThisTimestamp)
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}
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